Synthesis of aliphatic and alicyclic ethers

ABSTRACT

Aliphatic and alicyclic hydroperoxides and peroxides in the presence of a suitable alcohol and acid catalyst are converted to the corresponding ethers.

United States Patent Turner 1 Dec. 5, 1972 [541 SYNTHESIS OF ALIPHATICAND ALICYCLIC ETHERS [72] Inventor: John O. Turner, West Chester, Pa.

[73] Assignee: Sun Oil Company, Philadelphia, Pa.

[22] Filed: Oct. 31, 1969 [21] Appl. No.1 873,094

[52] US. Cl. ..260/611 R, 260/614 R [51] Int. Cl ..C07c 41/10 [58] Fieldof Search ..260/6l0 R, 614 R,6ll R 3,337,639 8/1967 Stedehouder et al..260/610 R Primary Examiner-Bernard Helfin Att0rneyGeorge L. Church,Donald R. Johnson,

Wilmer E. McCorquodale, Jr. and Stanford M. Back [57] ABSTRACT Aliphaticand alicyclic hydroperoxides and peroxides in the presence of a suitablealcohol and acid catalyst are converted to the corresponding ethers.

7 Claims, No Drawings SYNTHESIS OF ALIPHATIC AND ALICYCLIC ETHERSBACKGROUND OF THE INVENTION This invention relates to a novel processfor the preparation of aliphatic and alicyclic ethers. Moreparticularly, this invention relates to a process for the preparation ofaliphatic and alicyclic ethers by reacting the correspondinghydroperoxide or peroxide with a suitable alcohol in the presence of anacid catalyst.

Leffler, Chem. Revs. 45, 385 (1949) mentions the preparation ofisobutylene as the sole product in the decomposition oft-butylhydroperoxide with acid. In a related work, Davies et al., J.Chem. Soc., 2204 1954), reports the preparation of aralkyl peroxides bythe acid-catalyzed decomposition of the corresponding hydroperoxides.Maslennikov et al., Tr. Khim. i Khim. TerhnoL, 59 (1965), 'on the otherhand, teach the decomposition of t-butylhydroperoxide withbenzenesulfonic acid to form acetone and methanol. I

Thus, nowhere in the knownliterature is there any suggestion that ethersmay be prepared from hydroperoxides or peroxides. On the contrary, onlytwo well-known methods for the preparation of aliphatic ethers arerecognized today: (1) the reaction of an alkyl halide with an alkalimetal alkylate, and (2) the reaction of an olefin with an alcohol inacid.

SUMMARY OF THE INVENTION In accordance with the present invention, ithas now been found that aliphatic and alicyclic ethers may be preparedby reacting the corresponding hydroperoxide or peroxide with a suitablealcohol in the presence of an acid catalyst.

DESCRIPTION OF THE INVENTION This process is conveniently carried out bysimply mixing the desired hydroperoxide or peroxide starting material ina suitable alcoholic acid medium for about 4 to 40 hours, and preferablyfrom to 20.hours, depending upon the nature of the starting material,the concentration of the acid, etc., and recovering the resulting ether.

For optimum results, it is important that the ratios of thehydroperoxide or peroxide starting material, the acid, and the selectedalcohol be kept within certain ranges. Thus, the amount of alcoholshould be present in a two-to-twelve-fold molar excess, based on themolesof the hydroperoxide or peroxide starting material, and preferablyfrom about a seven-to-ten-fold molar excess of the alcohol.

The amount of acid should, in turn, be based on the amount of alcoholpresent in order to provide a to 65 weight percent concentration of acidbased on the total weight of the acid/alcohol mixture. The preferredweight percent of acid is about 50 to 55 percent. In carrying out thisreaction, it has been found to be particularly advantageous, afterremoving the ether from the reaction mixture, to recycle the acid to thereaction medium after addition of sufficient alcohol to readjust theacid concentration, thereby enhancing the yield of ether which isotherwise entrapped with the acid.

The acid employed should be a concentrated acid, as for examplehydrochloric, phosphoric, polyphosphoric, sulfuric, perchloric, varioussulfonic acids or the like,

as well as acid-treated molecular sieves, and preferably sulfuric acid.

The alcohol is desirably a lower, aliphatic alcohol having from one tofour carbon atoms. Of these, methanol is preferred. However, dependingupon the alkyl moiety desired in forming the resulting ether, otheralcohols may be employed instead. Thus, for example, if ethyl t-butylether is desired rather than methyl t-butyl ether, then ethanol shouldbe selected in place of methanol as the reactant.

The temperature employed in effecting this reaction. should desirably befrom about 20 to C, and preferably from 50 to 60 C.

The hydroperoxides and peroxides employed as starting materials in thisprocess include both aliphatic and alicyclic compounds which may haveanywhere from three to 12 carbon atoms.

The hydroperoxides may beeither secondary or tertiary compounds,although the latter type are more reactive and more effectively employedthan are the secondary compounds. Typical amongst the aliphaticcompounds which may be employed are such compounds ast-butylhydroperoxide, or sec.-butylhydroperoxide, and the correspondingperoxides, as

well as such alicyclic compounds as l-methylcyclopentyl andl-methylcyclohexyl hydroperoxide or peroxide, and the like.

When these and similar hydroperoxides or peroxides are treated inaccordance with this process there are obtained the correspondingaliphatic and alicyclic ethers such as alkyl t-butyl ether, alkylsec.-butyl ether, 1-methylcyclopentyl alkyl ether, and the like.

While applicant does not wish to be bound by any particular theoriesconcerning the mechanism of his reaction, it is believed that when thehydroperoxide is employed as the starting material some of it isconverted into the corresponding peroxide which, in turn, is thendecomposed to form the desired ether. Evidence for this is found in therecovery of peroxide from the reaction medium within relatively shortperiods after the reaction has commenced, i.e., within about the first10 hours. The peroxide does, however, disappear with time as the amountof ether increases.

Thus it will be evident that when the hydroperoxide is used as thestarting material the reaction conditions of time, temperature and acidconcentration may be varied somewhat within their given parameters tochange the rate at which the ether is recovered, and the amount ofperoxide intermediate which is formed. The rate at which peroxide isconverted to an ether, either as a starting material or as anintermediate will likewise be affected except that the reaction timewill, of course, be somewhat less than that for a comparable amount ofhydroperoxide. Generally speaking, the rate in either case will increasewith temperature and acid concentration. It will also be evident fromthe foregoing that mixtures of hydroperoxides and peroxides-may beemployed as the starting materials for this process.

The following examples illustrate the invention.

EXAMPLE 1 Nine grams (0. l moles) of t-butylhydroperoxide was slowlyadded to a solution of 36.3 grams of 96 percent sulfuric acid in 29.7grams of methanol. The solution was stirred for 18 hours at 50C atatmospheric pressure.

The product was collected by stripping the reaction solution underreduced pressure. Analysis showed it to be 4.4 grams (0.05 moles) ofmethyl t-butyl ether, 1.48 grams (0.02 moles) of methyl acetate and 10.0grams of methyl alcohol.

EXAMPLE 2 The procedure of Example 1 as applied to 14.6 grams (0.] mole)of dimethylneopentyl hydroperoxide yields 2.9 grams (0.02 mole) of thecorresponding methyl ether.

EXAMPLE 3 The procedure of Example 1 as applied to 5.8 grams (0.05 mole)of l-methylcyclopentyl hydroperoxide in MeOl-l-H SO yields 1.24 grams(0.01 mole) of the corresponding methyl ether.

EXAMPLE 4 The procedure of Example] as applied to 9 grams (0.1 mole) oft-BuOOI-i in 50 weight percent solution of' 96 percent H 80 in ethanolyields 2.45 grams (0.024 mole) of ethyl t-butyl ether.

EXAMPLE 5 In accordance with the procedure of Example 1 a solution madeup of 90 grams of 100 percent phosphoric acid in 50 grams of methanolwas heated with 9 grams (0.1 mole) of t-butylhydroperoxide. The reactionwas stirred for 18 hours at 70C and yielded 0.049 moles of methylt-butyl ether.

EXAlVlPLE 6 In accordance with the procedure of Example 1 a solutionmade up of 58 grams of p-toluene sulfonic acid in 60 grams ofisopropanol was treated with 9 grams (0.1 mole) of t-butylhydroperoxide.The reaction was stirred at 60C for 60 hours to yield 4.4 grams (0.038mole) of isopropyl t-butyl ether.

. EXAMPLE 7 Three separate runs were carried out as shown in thefollowing table wherein 7.3 grams (0.05 mole) of di-tbutylperoxide wasstirred in a 50 percent methanolic sulfuric acid at 50C under varyingconditions. The methanolic sulfuric acid medium was formed by mixing 33grams of methanol with 33 grams of concentrated sulfuric acid. The finalproduct, methyl t-butyl ether,

l. A process for the preparation of aliphatic or alicyclic ethers whichcomprises reacting a secondary or tertiary aliphatic or alicyclichydroperoxide or peroxide having from three to 12 carbon atoms with a C,prlmary or secondary alcohol 111 the presence of an ac:

catalyst selected from the group consisting of hydrochloric, phosphoric,polyphosphoric, sulfuric, perchloric and sulfonic acids, andacid-treated molecular sieves, at a temperature of from about 20 to 80C,wherein said alcohol is present in amounts of at least two molar excessbased on the weight of the peroxide or hydroperoxide starting materialand wherein the acidconcentration is from about 30 to 65 weight percentbased on the weight of the acid-alcohol mixture.

2. The process according to claim 1 wherein the acid concentration isfrom about 50 to 55 weight percent based on the weight of theacid-alcohol mixture.

3. The process according to claim 1 wherein the alcohol is methanol.

4. The process according to claim 1 wherein the alcohol is present in aseven-to-ten fold molar excess based on the number of moles of thehydroperoxide or peroxide starting material.

5. The process according to claim 1 wherein the starting material ist-butylhydroperoxide or t-butylperoxide, the alcohol is methanol and theproduct is methyl t-butylether.

6. The process according to claim 1 wherein the reaction is carried outfor at least 4 hours.

7. The process according to claim 1 for the production of methylt-butylether which comprises reacting tbutylhydroperoxide ort-butylperoxide or mixtures thereof with a to weight percent ofmethanolic sulfuric acid solution at about 50 to 55C for at least about4 hours, said methanol being present in a molar excess of at least twicethe number of moles of said hydroperoxide or peroxide starting material.

2. The process according to claim 1 wherein the acid concentration isfrom about 50 to 55 weight percent based on the weight of theacid-alcohol mixture.
 3. The process according to claim 1 wherein thealcohol is methanol.
 4. The process according to claim 1 wherein thealcohol is present in a seven-to-ten fold molar excess based on thenumber of moles of the hydroperoxide or peroxide starting material. 5.The process according to claim 1 wherein the starting material ist-butylhydroperoxide or t-butylperoxide, the alcohol is methanol and theproduct is methyl t-butylether.
 6. The process according to claim 1wherein the reaction is carried out for at least 4 hours.
 7. The processaccording to claim 1 for the production of methyl t-butylether whichcomprises reacting t-butylhydroperoxide or t-butylperoxide or mixturesthereof with a 50 to 55 weight percent of methanolic sulfuric acidsolution at about 50* to 55*C for at least about 4 hours, said methanolbeing present in a molar excess of at least twice the number of moles ofSaid hydroperoxide or peroxide starting material.